A rotating airfoil component of a turbomachine, in which the component has an airfoil aligned in a spanwise direction of the component, a shank, and a platform therebetween oriented transverse to the spanwise direction. The platform has an outer radial surface adjacent the airfoil, and at least one recessed region defined in its outer radial surface. The recessed region extends opposite the spanwise direction from a platform plane that contains portions of the outer radial surface that are upstream and downstream from the recessed region. The recessed region is contiguous with an end wall of the platform and extends therefrom toward the airfoil. The recessed region defines a surface shape whose boundary is contained by the platform plane, and has a profile shape that extends from the end wall toward the airfoil. The recessed region is sized and shaped to increase the stiffness of the platform.